Multielectrode electrographic printing device

ABSTRACT

In an electrographic printing device there is provided a carrier that forms a unit with the printing head and which also carries the electronic control components that selectively apply a potential to the electrodes arranged in the printing head. The platen is carried by a platen supporting mechanism by means of which the platen can be lifted off the printing head.

United States Patent n91 Nowak 1 Sept. 16, 1975 1 MULTIELECTRODE ELECTROGRAPHIC PRINTING DEVICE [75] Inventor: Gerald Nowak, Neusatz, Germany [73] Assignee: Olympia Werke AG,

Wilhelmshaven, Germany [221 Filed: Feb. 20, I974 [21] Appl. No.: 444,l02

3,670,861 6/1972 Zewner et a1. 197/1 R X 3,710,913 1/1973 Brennan 1 1. 346/76 R X 3,744,611 7/1973 Montanari et a1. 197/] R 3,754,278 8/1973 Borden, Jr. 346/76 R 3,787,886 1/1974 McCrady 346/76 R R18,158 8/1931 Myers et all 197/149 FOREIGN PATENTS OR APPLICATIONS 439,596 12/1935 United Kingdom .1 197/149 1,178,241 9/1964 Germany 1 346/76 1,245,181 9/1965 Germany 346/76 Primary Examiner.l. Reed Fisher Assistant Examiner-R. T. Rader Armrne Agent, or Firm-Spencer & Kaye [57] ABSTRACT In an electrographic printing device there is provided a carrier that forms a unit with the printing head and which also carries the electronic control components that selectively apply a potential to the electrodes arranged in the printing head. The platen is carried by a platen supporting mechanism by means of which the platen can be lifted off the printing head.

19 Claims, 5 Drawing Figures PATENIEU SEP 1 6 975 SHEET 2 [IF 3 FIG.2

PATENTED SEP 1 6 i975 SHEET 3 [1F 3 MULTIELECTRODE ELECTROGRAPHIC PRINTING DEVICE BACKGROUND OF THE INVENTION This invention relates to an electrographic printing device which includes a plurality of electrodes disposed side-by-side in a printing head. The electrodes are controlled by electronic control components. The printing device is further of the type that has a platen which, in cooperation with the electrodes, guides a currentresponsive imprint carrier and unwinds it from a supply roll.

In a known electrographic printing device of the aforenoted type, as disclosed in German Laid Open Patent application (Offenlegungsschrift) 2,150,343, an imprint carrier running off a supply roll is advanced over several guide rolls to a motor-driven platen on which there are disposed the electrodes of a removable printing head. The electrodes are connected by means of individual cables with electronic control components to selectively apply an electric potential to the electrodes. This type of printing device proved to be disadvantageous in that, because of the arrangement of the stationarily supported guide rollers and platen, the insertion of a new supply roll and the threading of the imprint carrier into the device are very difficult even if the printing head is lifted 05. Further, the volume of the entire printing device is increased in an undesirable manner.

SUMMARY OF THE INVENTION It is an object of the invention to provide an improved electrographic printing device which is free from the disadvantages of the prior art, which requires small structural space, which is of simple economical construction and which, nevertheless, ensures a faultless guidance of the imprint carrier and which simplifies the threading of the imprint carrier and reduces the time required therefor.

These objects and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the printing head constitutes a structural unit with a carrier for the electronic control components and the driven platen is removable from the printing head.

The invention is further advantageous in that, by virtue of the rigid connection of the printing head with the electronic control component carrier, the heretofore necessary coupling cable (such as a l-pole cable tree for a printing head spanning 20 positions with 5 electrodes each) may be omitted and that, by virtue of the movable arrangement of the platen, the insertion (threading) of the imprint carrier taken from the supply roll is substantially facilitated. By moving the platen into its operational position, the imprint carrier not only assumes a position by itself between the platen and the printing head (the electrodes of which function as a counter-roll), but the imprint carrier also positions itself to such an extent about the platen that it is thereafter advanced by the platen in cooperation with the electrodes pressed thereagainst.

Further developments of the invention have additional advantages. The structure of the printing device can be substantially simplified by arranging the printing head as well as the electronic component carrier in a lower part of the printing device an to arrange the platen as well as its drive motor in an upper part of the printing device. The upper part is hingedly supported by the lower part.

For a simple replacement of the printing head, the invention provides that the carrier for the electronic control components is a conductor plate which receives the printing head by means of a plug-in bar affixed to the printing head.

The advantage of favorable structural dimensions and a good legibility of the printed imprint carrier are accomplished in particular if the removable platen is disposed behind (as viewed by an observer) the printing head and the imprint carrier is threaded from below upwardly betwen the electrodes and the platen.

For pressing the platen against the electrodes or, as the case may be, against the imprint carrier guided between these two components, the hinging upper part of the printing device may be linearly displaceably supported with respect to the lower part and may be biased by at least one spring. For this purpose, in the lower part there is supported at least one upright, swingable lever which is articulated to the upper part of the printing device.

Prior to tearing off the imprint carrier against the severing bar of the printing device, the imprint carrier should be advanced by the platen to such an extent that the last imprinted mark on the imprint carrier lies above the severing bar. For accomplishing this in a simple manner, according to a further development of the invention, the lever includes a slot which extends in the pivotal direction of the lever and into which projects a pin of the upper part. Further, at the lower part there is provided a drive motor switch which can be actuated by the lever. The switch is disposed in such a manner that, by virtue of moving the lever in the one direction, the upper part is linearly shifted and by moving the lever in the other direction, the switch is closed.

According to another embodiment of the invention, for pressing the electrodes against the platen, or, as the case may be, against the imprint carrier guided between these two components, the carrier is, with the printing head, linearly displaceably supported in the lower part and is biased by at least one spring. In order to securely prevent a damaging of the electrodes which are pressed against the platen or the imprint carrier during the upward swinging of the upper part, the electrodes can be shifted off the platen by providing a lever which is supported in the lower part and by means of which the carrier with the printing head, is displaceable against the force of a spring. Only after this removal of the electrodes is the upper part which, in its working position, is locked to the lower part released by the manually operated lever and may be swung upwardly together with the platen. Expediently, for the imprint carrier there is provided a deflecting roller and on the carrier there is provided a spring-biased counter-roller, the spring of which swings the upper part upwardly after the latter is unlocked from the lower part.

In order to prevent the platen from being driven when there is no imprint carrier between the platen and the electrodes, according to the invention there is provided a circuit which, when the imprint carrier runs out, is closed by the counter-roller and the deflecting roller for stopping the drive motor of the platen.

According to a further development of the invention, there is performed an automatic cleaning of the electrodes of the printing head every time a new supply roll is inserted or when the upper part of the printing device is swung down. This automatic cleaning is accomplished by providing on the lower part or on the carrier, a holder positioning a brush which extends parallel to the electrodes. This holder is displaceable for cleaning the electrodes when the upper part is in a down-swung position. The pivotal brush holder may be spring-biased and may be immobilized or released by the upper part. During such a step, the brush moves over the electrodes and effects a cleaning thereof. The holder is expediently provided with a severing bar with the aid of which the imprint carrier may be torn off when the holder is in the stand-by, locked position.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic, partially sectional side elevational view of a first embodiment of the printing device depicted in its working position.

FIG. 2 is a perspective view of some components of FIG. 1.

FIG. 3 is a schematic, partially sectional side elevational view of a second embodiment of the printing device.

FIGS. 4a and 4b illustrate a safety circuit incorporated in the first embodiment in a de-energized and energized state, respectively.

DETAILED DESCRIPTION OF THE EMBODIMENTS Turning now to FIGS. 1 and 2, the electrographic printing device shown therein comprises a lower part 1, and an upper part 2 which is pivotally attached to the lower part 1 by means of a shaft 3 to be swingable upwardly (clockwise) from its position shown. In the lower part 1, there is disposed a carrier 4 which is formed of a conductor plate 5 and a cover plate 6. The plates 5 and 6 are, as well seen in FIG. 2, rigidly connected with one another by two laterally arranged U- shaped brackets 7. The cover plate 6 of the carrier 4 has at both sides laterally projecting tabs 8 which may be inserted into upwardly partially open, horizontal slots 9 of the lower part 1. The tabs 8 are supported slidably in the slots 9.

On the conductor plate 5 of the carrier 4, there is mounted a printing head 10 by means of a plug-in bar 11 which permits a simple replacement of the printing head 10. The latter has a plurality of juxtaposed electrodes l2 and projects through an opening 13 of the cover plate 6. On the conductor plate 5 there are further arranged known electronic control components 14, for example, for decoding. These components 14 control the electrodes 12 by selectively applying a voltage thereto. The conductor plate 5, the cover plate 6, the printing head 10 and the electronic control components 14 thus constitute a unit displaceably supported in the lower part 1 of the printing device.

The lower part 1 pivotally supports a manually operable lever 15 which, cooperating with the tabs 8 of the cover plate 6, may displace the carrier 4 against the force of two springs 16. These springs are tensioned between posts 17 (only one shown in FIG. 1) of the cover plate 6 and the shaft 3. The cover plate 6 further carries a supply roll 18. For the accommodation and support of the supply roll 18 there are provided, in the cover plate 6, an opening 19 corresponding to the width of the supply roll 18 and a floor plate 20 disposed thereunder. The supply roll 18 is positioned only loosely on the floor plate 20 and is maintained in positon by the edges of the opening 19.

In the upper part 2 there are disposed a platen 21 sit- 5 uated opposite the electrodes 12 of the printing head 10, a drive motor 22 for rotating the platen 21 with a gear drive 23 and an idling deflecting roller 24. Below the cover plate 6 there is disposed a leaf spring 25 with an idling counter-roller 26 which projects through the opening 13 of the cover plate 6 and which is pressed against the deflecting roller 24 of the upper part 2. The upper part 2 further has at least one hook-shaped projection 27 extending through the cover plate 6. The upper part 2 may be locked by means of the cooperation between the projection 27 and the displaceable cover plate 6. From the supply roll 18 there is drawn off a current-sensitive imprint carrier 28 which is guided in an upward direction between the deflecting roller 24 and the counter-roller 26, then between the electrodes 12 of the printing head 10 and the driven platen 21. The weight of the supply roll 18 produces the pressure force for the braking of the imprint carrier 28 as it is being drawn from the supply roll 18.

In the closed (working) position of the upper part 2 as illustrated in FIG. 1, the springs 16 draw the carrier 4 and thus the printing head 10 rearwardly (towards the right as observed in FIG. I). In this manner, the electrodes 12 of the printing head 10 are brought into contact with the current-sensitive imprint carrier 28. The electrodes serve for the printing of information such as letters, digits or other marks. To one or several electrodes 12 which are connected with the electronic control components 14 through the plug-in bar 11 and the conductor plate 5 an electric potential is applied. The counter-roller 26 is designed as a counterelectrode so that, by virtue of the electrodes 12 to which an electric potential had been applied, holes are burned in the imprint carrier 28 to provide dots arranged in a raster pattern. Thus, on the imprint carrier 28 each information is formed of, for example, 5 X 7 legible raster dots composed in a mosaic-like manner. The dots of each information are thus arranged in five vertical columns, seven dots each. The printing device utilizes only the five electrodes belonging to a mosaic cell associated with one information. The electrodes, during the course of a seven-fold energization with a simultaneous shift of the imprint carrier 28 by the platen 21, write the information line-by-line and perpendicularly with respect to the arrangement of the electrodes 12. It is to be understood that several groups of five electrodes 12 each may be arranged in the direction of a printing line in which case, then, all the characters of one printing line are composed simultaneously.

It is a significant feature of the invention that the platen 21 on which the imprint carrier 28 is provided with information is arranged rearwardly of the printing head 10. Or, stated differently, the platen 21 is situated between the printing head 10 and the shaft 3, in close vicinity of the printing head 10. The imprint carrier 28 then runs from the rearwardly located supply roll 18 forwardly; it is subsequently guided upwardly by the deflecting roller 24 and is guided upwardly between the electrodes 12 and the platen 21 so that the information on the imprint carrier 28 is presented in the desired sequence and in a clearly visible manner. It is of particular advantage that the drive of the imprint carrier 28 is effected directly at the location of printing by virtue of the cooperation between the platen 21 and the electrodes I2 which function as counter-rollers. Thus, the provision of a separate drive means is not necessary. It is expedient here to make the driven platen 21 ofa ma terial, such as a synthetic material, which has a high constant coefficient of friction, since the magnitude of friction between the electrodes l2 and the metallized surface of the imprint carrier 28 is relatively small.

For replacing the supply roll 18, the lever is piv oted counterclockwise. As a result, the carrier 4 is shifted forward (to the left) against the force of the springs 16. Such a forward shift is made possible by the cooperation between the tabs 8 ofthe cover plate 6 and the slots 9 of the lower part 1. The electrodes 12 of the printing head I" are thus pulled away from the imprint carrier 28 or the platen 2|, as the case may be, so that a damaging of the electrodes 12 during the subsequent upward pivoting of the upper part 2 is reliably prevented. The displaced cover plate 6 releases the hookshaped projection 27 of the upper part 2, permitting the leaf spring to slightly pivot the upper part 2 upwardly by virtue of its force exerted on the upper part 2 through the counter-roll 26 and the deflecting roll 24. Thereafter, the upper part 2 may be entirely swung open upwardly (clockwise) by hand.

After insertion of a new supply roll 18 into the opening I) of the cover plate 6, the leading end of the imprint carrier 28 is pulled off the supply roll 18 and positioned in a forward orientation. By pivoting the upper part 2 downwardly, the left-hand oblique face 29 of the hook-shaped projection 27 presses the cover plate 6 and thus the printing head 10 toward the left to prevent damaging of the electrodes 12. Simultaneously, the imprint carrier 28 automatically positions itself between the deflecting roller 24 and the counter-roller 26 as well as between the platen 21 and the electrodes 12. In the working position of the upper part 2, the oblique face 29 of the projection 27 releases the cover plate 6, the springs 16 of which draw the entire carrier 4 with the printing head 10 toward the right. In this manner the upper part 2 is locked and the electrodes 12 are pressed against the imprint carrier 28 and the platen 2]. At the same time, the imprint carrier 28 positions itself automatically to such an extent about the platen 2] that the imprint carrier 28 is transported by the driven platen 21 as the latter cooperates with the printing electrodes [2 which function as a pressure counterroll.

On the covering plate 6 of the carrier 4 there is pivotally supported a holder 30 having two V-shaped lateral plates. Between the upper legs of these lateral plates there extends a severing bar 31 which is oriented parallel to the electrodes 12 and at which the imprint carrier 28 may be torn off. Between the lower legs of the lateral plates there extends a brush 32 oriented parallel to the electrodes 12 and having bristles pointing forward (towards the left). The holder 30 is biased by a spring 33 and is maintained against the force of the spring 33 in its illustrated working position by the closed upper part 2. During each replacement ofa supply roll 18, the holder 30 is released by virtue of opening of the upper part 2, so that the holder 30, urged by the force of the spring 33, pivots in a counterclockwise direction. As a result, the brush 32 slidingly contacts the electrodes 12 thus effecting a cleaning thereof.

In order to prevent die platen 2] from being driven when there is no imprint carrier 28 between the platen 2| and the electrodes 12, the electrographic printing device may include an electric safety circuit for de- 5 energizing the drive motor 22 of the platen 21. An example of such a safety circuit is illustrated in FIGS. 4a and 4b and is generally indicated at 60. According to this example, the deflecting roller 24 and the counterroller 26 are both electrically conductive and are connected in series with a current source and the coil of a relay 6]. The latter has normally closed contacts 62 which constitute a circuit breaker switch for the drive motor 22. FIG. 4a depicts the circuit 60 in an open (deenergized) state, since the imprint carrier 28 passing 5 between rollers 24 and 26 prevents an electric contact therebetween. Thus, the relay switch 62 is maintained closed and consequently, the motor 22 is maintained in an energized or energizable state. The moment the trailing end of the imprint carrier 28 runs out from between the rollers 24 and 26, the circuit 60 assumes its closed (energized) state depicted in FIG. 4!). By virtue of the contacting between the rollers 24 and 26 the circuit 60 is closed, whereby the relay 61 is energized causing opening of the switch 62. The opening of the switch 62, in turn, causes de-energization (or prevents energization) of the drive motor 22 for the platen 21.

Turning now to FIG. 3, the embodiment of the electrographic printing device shown therein comprises, similar to the previously described embodiment, a lower part 34 and an upper part 35 which, in addition to its pivotal attachment to the lower part 34, is arranged for linear displacement with respect to the lower part 34. In the lower part 34 there is fixedly arranged a carrier 34a for the electronic control components 35b. To the carrier 34a there is secured a printing head 36 with electrodes 37 by means of a plug-in bar 36a. At the rearward (right-hand) end of the lower part 34 there is pivotally supported a lever 39 biased by a spring 38. The lever 39 is in its middle zone provided with a slot 40 extending in the pivotal direction of the lever 39. Into the slot 40 there projects a pivot pin 4! of the upper part 35. A spring 42 is tensioned between the pin 41 or the upper part 35 and a hook 43 of the lower part 34. Expediently, at each side of the printing device there is provided a spring 42.

In the upper part 35 there are arranged a drive motor 44, a drive gear 44a and a platen 45 which, in its working position, is disposed opposite the electrodes 37 of the printing head 36. Further, the upper part 35 has a hook-shaped projection 46 which, in the closed position of the upper part 35, hooks under a web 47 of the lower part 34. In the lower part 34 there is further provided a microswitch 51 and a pivotal holder 49 which is biased by a spring 48 and which serves for carrying a severing bar 50. The microswitch 51 is situated in the travelling path of the lever 39 to be actuated by the latter for energizing the drive motor 44 of the platen 45.

In the working position of the printing device the springs 42 draw the upper part 35 towards the left through the pin 41, so that the platen 45 is pressed resiliently against the electrodes 37 of the printing head 36 or, as the case may be, against the imprint carrier 52 disposed between the platen 4S and electrodes 37. The imprint carrier 52 is wound on a supply roll 53. For a replacement of the supply roll 53, the lever 39 is manually pivoted about the axis of pin 41 in the direction of the arrow 54. As a result, by virtue of the cooperation between the left-hand border of the slot 40 and the pin 41, the upper part 35 is shifted towards the right with respect to the lower part 34 into its dash-dotted position, whereby the platen 45 is pulled away from the printing head 36. A damaging of the electrodes 37 during the subsequent upward pivoting of the upper part 35 is thus securely prevented. Further, the hookshaped projection 46 of the upper part 35 has cleared the web 47 of the lower part 34 so that the upper part 35 can now be pivoted upwardly.

After the insertion of a new supply roll 53 into the lower part 34, the leading end of the imprint carrier 52 is reeled off the supply roll 53 and is positioned in a forward (leftward) orientation. During the downward (counterclockwise) pivoting of the upper part 35, the oblique surface 55 of the hook-shaped projection 46 slides along the edge of the web 47 of the lower part 34 and thus displaces the upper part 35 towards the right into its dash-dotted position. in the fully closed position of the upper part 35, the hook-shaped projection 46 hooks under the web 47 and the springs 42 draw the upper part 35 forward (towards the left) into a locked working position. Further, during downward (counterclockwise) pivoting of the upper part 35, a protruding nose 56 thereof abuts against a surface 57 of the holder 49 which, as a result, is pivoted with the upper part 35 clockwise against the force of the spring 48 from the dash-dotted position into the full-line position and is maintained securely in the latter by the closed upper part 35. At the same time, the imprint carrier 52 automatically positions itself about the driven platen 45 to such an extent that it is advanced by the platen 45 in cooperation with the printing electrodes 37 urged into contact with the imprint carrier 52.

Prior to tearing off the imprint carrier 52 against the severing bar 50, the imprint carrier 52 has to be advanced forwardly (upward) to such an extent that the last imprinted information is disposed above the tearing edge of the severing bar 50. For this purpose, there is provided the microswitch 51 which is closed by the lever 39 as the latter is moved in the direction of the arrow 58 against the force of the spring 38, whereby the drive motor 44 of the platen 45 is energized. The upper part 35 is, by virtue of the provision of the slot 40 in the lever 39, not affected. The imprint carrier 52 is moved upwardly as long as the lever 39 is pulled forwardly. After releasing the lever 39, the latter is, by virtue of the spring 38, reset into its full-line position in which the microswitch 51 is again opened. The imprint carrier 52 can now be torn off at the severing bar 50. For permitting a continuous inspection of the condition of the supply roll 53 during operation of the printing device, the upper part 35 is expediently provided with a transparent dust cover 59.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.

I claim:

1. In an electrographic printing device having a printing head, a plurality of juxtaposed electrodes mounted on the printing head, electronic control components supported in the device and coupled to the electrodes for selectively applying an electric potential thereto, a platen situated adjacent the electrodes. means supporting a supply roll of current-sensitive imprint carrier and means guiding the imprint carrier between the electrodes and the platen; the improvement comprising in combination:

a. a carrier disposed in the device, said carrier sup porting said electronic control components and said printing head, said carrier and said printing head constituting a unit;

b. a lower part forming a portion of said device; said printing head and said carrier are held in said lower part;

c. a drive motor coupled to said platen for rotating the same; and

d. an upper part pivotally secured to said lower part; said platen and said drive motor are held in said upper part, said upper part constituting a platen supporting means having a first position in which said platen is held in a working position adjacent said printing head and a second position in which said platen is in a lifted-off position with respect to said printing head.

2. A device as defined in claim 1, further including (e) a plug-in bar affixed to said printing head; and

(f) a conductor plate constituting said carrier; said plug-in bar being attached to said conductor plate for supporting said printing head on said conductor plate.

3. A device as defined in claim 1, wherein said platen, when in said working position, is positioned between said printing head and the pivotal attachment between said upper and lower parts; the imprint carrier guiding means being arranged for advancing the imprint carrier in an upward direction in between said electrodes and said platen.

4. A device as defined in claim 1, further including (e) means for linearly displaceably attaching said upper part to said lower part; and

(f) spring means attached to said upper part, said spring means acting in the direction of the path of linear displacement of said upper part for urging said platen against said electrodes.

5. A device as defined in claim 4, further including an operating lever pivotally supported on said lower part and articulated to said upper part.

6. A device as defined in claim 5, further including means defining, in said operating lever, a slot oriented in the direction of pivotal movement of said operating lever; a pin affixed to said upper part and projecting into said slot; and a switch supported in said lower part and connected to said drive motor, said switch being situated in the path of motion of said lever to be operable by the latter; said operating lever being arranged to linearly displace said upper part in a direction away from said printing head when said operating lever is pivoted in the one direction, said operating lever being further arranged to contact said switch for energizing said drive motor when said operating lever is moved in the other, opposite direction.

7. A device as defined in claim 1, further including (e) means for linearly displaceably supporting said carrier in said lower part; and

(f) spring means attached to said carrier, said spring means acting in the direction of the path of linear displacement of said carrier for urging said printing head against said platen.

8. A device as defined in claim 7, further including .ixJUi-iol tg) nit-runs defining slots on opposite sides ot said lower part. said slots are oriented in the direction of linear displacement of said carrier; and

(h) lateral projections attached to and extending in opposite directions from said carrier, said lateral projections are disposed in and cooperate with said slots for providing a guidance for the linear displacement of said carrier.

9. A device as defined in claim 7, further including an operating lever pivotally supported on said lower part and connected to said carrier for displacing the latter against the force of said spring means.

10. A device as defined in claim 5, further including locking means for locking said upper part to said carrier when said platen is in its working position, said locking means being arranged for release when said upper part is linearly displaced upon manipulation of said operating lever.

11. A device as defined in claim 10, wherein said locking means includes at least one hook-shaped projection affixed to said upper part and means defining an opening in said carrier for receiving said hook-shaped projection.

12. A device as defined in claim 9, further including releasable locking means for locking said upper part to said carrier when said platen is in its working position, said locking means being arranged for release when said carrier is linearly displaced upon manipulation of said operating lever.

13. A device as defined in claim 12, wherein said locking means includes at least one hook-shaped projection affixed to said upper part and means defining an opening in said carrier for receiving said hook-shaped projection.

14. In an electrographic printing device having a printing head, a plurality of juxtaposed electrodes mounted on the printing head, electronic control components supported in the device and coupled to the electrodes for selectively applying an electric potential thereto, a platen situated adjacent the electrodes, means supporting a supply roll of current-sensitive imprint carrier and means guiding the imprint carrier between the electrodes and the platen; the improvement comprising in combination:

a. a carrier disposed in the device, said carrier supporting said electronic control components and said printing head, said carrier and said printing head constituting a unit;

b. platen supporting means held in said device and having a first position in which said platen is held in a working position adjacent said printing head and a second position in which said platen is in a lifted-off position with respect to said printing head;

c. a holder movably supported in said device adjacent said printing head;

d. a brush carried by said holder and arranged adjacent and parallel to said electrodes; and

e. means coupling said platen supporting means to said holder for causing movement thereof as said platen supporting means is moved out of its said first position; said brush being arranged to slide on stun \JiULin to ior cleaning the same upon movement of saitl holder.

15. A device as defined in claim 14, further including spring means attached to said holder for urging it in one direction of motion; said means coupling said platen supporting means to said holder includes a component for locking said holder when said platen supporting means is in said first position and releasing said holder when said platen supporting means is moved out of said first position.

16. A device as defined in claim 14, further including a severing bar attached to said holder and disposed adjacent and parallel to said platen.

17. In an electrographic printing device having a printing head, a plurality of juxtaposed electrodes mounted on the printing head, electronic control components supported in the device and coupled to the electrodes for selectively applying an electric potential thereto, a platen situated adjacent the electrodes, means supporting a supply roll of current-sensitive imprint carrier and means guiding the imprint carrier between the electrodes and the platen; the improvement comprising in combination:

a. a carrier disposed in the device, said carrier supporting said electronic control components and said printing head, said carrier and said printing head constituting a unit;

b. platen supporting means held in said device and having a first position in which said platen is held in a working position adjacent said printing head and a second position in which said platen is in a lifted-off position with respect to said printing head;

c. releasable locking means for locking said platen supporting means in said first position;

(1. a deflecting roller rotatably supported in said platen supporting means;

e. a counter-roller rotatably supported in said carrier;

and

f. spring means connected to said counter-roller for urging said counter-roller into contact with said deflecting roller to pinch the imprint carrier therebetween; said deflecting roller, said counter-roller and said spring means forming part of said means guiding the imprint carrier; said spring means being further arranged for moving said platen supporting means out of its said first position upon release of said locking means.

18. A device as defined in claim 17, wherein said counter-roller constitutes a counter-electrode cooper ating with said electrodes.

19. A device as defined in claim 17, further including a drive motor coupled to said platen for rotating the same and an electric circuit connected at least indirectly to said drive motor, said deflecting roller and said counter-roller; said electric circuit having an operative state for de-energizing said drive motor; said deflecting roller and said counter-roller being arranged to place said circuit in said operative state upon direct contact between said rollers. 

1. In an electrographic printing device having a printing head, a plurality of juxtaposed electrodes mounted on the printing head, electronic control components supported in the device and coupled to the electrodes for selectively applying an electric potential thereto, a platen situated adjacent the electrodes, means supporting a supply roll of current-sensitive imprint carrier and means guiding the imprint carrier between the electrodes and the platen; the improvement comprising in combination: a. a carrier disposed in the device, said carrier supporting said electronic control components and said printing head, said carrier and said printing head constituting a unit; b. a lower part forming a portion of said device; said printing head and said carrier are held in said lower part; c. a drive motor coupled to said platen for rotating the same; and d. an upper part pivotally secured to said lower part; said platen and said drive motor are held in said upper part, said upper part constituting a platen supporting means having a first position in which said platen is held in a working position adjacent said printing head and a second position in which said platen is in a lifted-off position with respect to said printing head.
 2. A device as defined in claim 1, further including (e) a plug-in bar affixed to said printing head; and (f) a conductor plate constituting said carrier; said plug-in bar being attached to said conductor plate for supporting said printing head on said conductor plate.
 3. A device as defined in claim 1, wherein said platen, when in said working position, is positioned between said printing head and the pivotal attachment between said upper and lower parts; the imprint carrier guiding means being arranged for advancing the imprint carrier in an upward direction in between said electrodes and said platen.
 4. A device as defined in claim 1, further including (e) means for linearly displaceably attaching said upper part to said lower part; and (f) spring means attached to said upper part, said spring means acting in the direction of the path of linear displacement of said upper part for urging said platen against said electrodes.
 5. A device as defined in claim 4, further including an operating lever pivotally supported on said lower part and articulated to said upper part.
 6. A device as defined in claim 5, further including means defining, in said operating lever, a slot oriented in the direction of pivotal movement of said operating lever; a pin affixed to said upper part and projecting into said slot; and a switch supported in said lower part and connected to said drivE motor, said switch being situated in the path of motion of said lever to be operable by the latter; said operating lever being arranged to linearly displace said upper part in a direction away from said printing head when said operating lever is pivoted in the one direction, said operating lever being further arranged to contact said switch for energizing said drive motor when said operating lever is moved in the other, opposite direction.
 7. A device as defined in claim 1, further including (e) means for linearly displaceably supporting said carrier in said lower part; and (f) spring means attached to said carrier, said spring means acting in the direction of the path of linear displacement of said carrier for urging said printing head against said platen.
 8. A device as defined in claim 7, further including (g) means defining slots on opposite sides of said lower part, said slots are oriented in the direction of linear displacement of said carrier; and (h) lateral projections attached to and extending in opposite directions from said carrier, said lateral projections are disposed in and cooperate with said slots for providing a guidance for the linear displacement of said carrier.
 9. A device as defined in claim 7, further including an operating lever pivotally supported on said lower part and connected to said carrier for displacing the latter against the force of said spring means.
 10. A device as defined in claim 5, further including locking means for locking said upper part to said carrier when said platen is in its working position, said locking means being arranged for release when said upper part is linearly displaced upon manipulation of said operating lever.
 11. A device as defined in claim 10, wherein said locking means includes at least one hook-shaped projection affixed to said upper part and means defining an opening in said carrier for receiving said hook-shaped projection.
 12. A device as defined in claim 9, further including releasable locking means for locking said upper part to said carrier when said platen is in its working position, said locking means being arranged for release when said carrier is linearly displaced upon manipulation of said operating lever.
 13. A device as defined in claim 12, wherein said locking means includes at least one hook-shaped projection affixed to said upper part and means defining an opening in said carrier for receiving said hook-shaped projection.
 14. In an electrographic printing device having a printing head, a plurality of juxtaposed electrodes mounted on the printing head, electronic control components supported in the device and coupled to the electrodes for selectively applying an electric potential thereto, a platen situated adjacent the electrodes, means supporting a supply roll of current-sensitive imprint carrier and means guiding the imprint carrier between the electrodes and the platen; the improvement comprising in combination: a. a carrier disposed in the device, said carrier supporting said electronic control components and said printing head, said carrier and said printing head constituting a unit; b. platen supporting means held in said device and having a first position in which said platen is held in a working position adjacent said printing head and a second position in which said platen is in a lifted-off position with respect to said printing head; c. a holder movably supported in said device adjacent said printing head; d. a brush carried by said holder and arranged adjacent and parallel to said electrodes; and e. means coupling said platen supporting means to said holder for causing movement thereof as said platen supporting means is moved out of its said first position; said brush being arranged to slide on said electrodes for cleaning the same upon movement of said holder.
 15. A device as defined in claim 14, further including spring means attached to said holder for urging it in one direction of motion; said means couplinG said platen supporting means to said holder includes a component for locking said holder when said platen supporting means is in said first position and releasing said holder when said platen supporting means is moved out of said first position.
 16. A device as defined in claim 14, further including a severing bar attached to said holder and disposed adjacent and parallel to said platen.
 17. In an electrographic printing device having a printing head, a plurality of juxtaposed electrodes mounted on the printing head, electronic control components supported in the device and coupled to the electrodes for selectively applying an electric potential thereto, a platen situated adjacent the electrodes, means supporting a supply roll of current-sensitive imprint carrier and means guiding the imprint carrier between the electrodes and the platen; the improvement comprising in combination: a. a carrier disposed in the device, said carrier supporting said electronic control components and said printing head, said carrier and said printing head constituting a unit; b. platen supporting means held in said device and having a first position in which said platen is held in a working position adjacent said printing head and a second position in which said platen is in a lifted-off position with respect to said printing head; c. releasable locking means for locking said platen supporting means in said first position; d. a deflecting roller rotatably supported in said platen supporting means; e. a counter-roller rotatably supported in said carrier; and f. spring means connected to said counter-roller for urging said counter-roller into contact with said deflecting roller to pinch the imprint carrier therebetween; said deflecting roller, said counter-roller and said spring means forming part of said means guiding the imprint carrier; said spring means being further arranged for moving said platen supporting means out of its said first position upon release of said locking means.
 18. A device as defined in claim 17, wherein said counter-roller constitutes a counter-electrode cooperating with said electrodes.
 19. A device as defined in claim 17, further including a drive motor coupled to said platen for rotating the same and an electric circuit connected at least indirectly to said drive motor, said deflecting roller and said counter-roller; said electric circuit having an operative state for de-energizing said drive motor; said deflecting roller and said counter-roller being arranged to place said circuit in said operative state upon direct contact between said rollers. 